Text Box: Pre-op Instructions Animals must be crated or on a leash when you drop them off at the clinic. If the weather permits, please leave your animal in your vehicle during the check in process. It is best to have your pet fully vaccinated prior to surgery. Animals over 4 pounds Withhold food after midnight. Keep the pet indoors the night before surgery so that you are sure he/she did not eat. Animals 4 pounds and smaller DO NOT withhold food.